Study on Pressure Relief Technology Using Hydraulic Fracturing in Hard Roof Strata at Guqiao Mine

Abstract

During the mining of the adjacent working face at Guqiao Mine 1315(1), the hard roof proved difficult to collapse, leading to significant stress concentration in the coal pillars near the roadway. This study analyzes the causes of stress concentration in the coal pillars and proposes hydraulic fracturing and roof cutting as a mitigation method. Numerical simulations were conducted to determine the optimal roof-cutting angle and depth, followed by field trials. The results demonstrate that hydraulic fracturing effectively reduces stress on the coal pillar side and promotes roof caving in the goaf. A roof-cutting height of 28 m and an angle of 60° were found to be the most effective, shifting the stress concentration zone to 3.8 m from the 1315(1) track gateway, with a peak stress of 38.4 MPa-a reduction of 9.7 MPa or 20.1% compared to the scenario without roof cutting. The industrial application, guided by the simulated angle, yielded satisfactory outcomes.